#include <stdio.h>
#include <string.h>

//初始置换IP
int IP[] = {
            58, 50, 42, 34, 26, 18, 10, 2, 
            60, 52, 44, 36, 28, 20, 12, 4,
            62, 54, 46, 38, 30, 22, 14, 6, 
            64, 56, 48, 40, 32, 24, 16, 8,
            57, 49, 41, 33, 25, 17,  9, 1, 
            59, 51, 43, 35, 27, 19, 11, 3,
            61, 53, 45, 37, 29, 21, 13, 5,
            63, 55, 47, 39, 31, 23, 15, 7 
};
//逆初始置换IP
int _IP[] = {
            40, 8, 48, 16, 56, 24, 64, 32,
			39, 7, 47, 15, 55, 23, 63, 31,
			38, 6, 46, 14, 54, 22, 62, 30,
			37, 5, 45, 13, 53, 21, 61, 29,
			36, 4, 44, 12, 52, 20, 60, 28,
			35, 3, 43, 11, 51, 19, 59, 27,
			34, 2, 42, 10, 50, 18, 58, 26,
			33, 1, 41,  9, 49, 17, 57, 25
};
//置换选择1
int IP_1[] = {
            57, 49, 41, 33, 25, 17, 9,  
             1, 58, 50, 42, 34, 26, 18,
            10,  2, 59, 51, 43, 35, 27, 
            19, 11,  3, 60, 52, 44, 36, 
            63, 55, 47, 39, 31, 23, 15, 
             7, 62, 54, 46, 38, 30, 22,
            14,  6, 61, 53, 45, 37, 29,
            21, 13,  5, 28, 20, 12,  4 
};
//置换选择2
int IP_2[] = {
            14, 17, 11, 24,  1,  5,  
             3, 28, 15,  6, 21, 10,
            23, 19, 12,  4, 26,  8, 
            16,  7, 27, 20, 13,  2,
            41, 52, 31, 37, 47, 55, 
            30, 40, 51, 45, 33, 48,
            44, 49, 39, 56, 34, 53, 
            46, 42, 50, 36, 29, 32
};
//循环左移位数表
int left_16[] = {
            1, 1, 2, 2, 2, 2, 2, 2,
            1, 2, 2, 2, 2, 2, 2, 1
};
//选择运算E
int expand_48[] = {
            32,  1,  2,  3,  4,  5, 
             4,  5,  6,  7,  8,  9,
             8,  9, 10, 11, 12, 13,
            12, 13, 14, 15, 16, 17,
            16, 17, 18, 19, 20, 21,
            20, 21, 22, 23, 24, 25,
            24, 25, 26, 27, 28, 29,
            28, 29, 30, 31, 32,  1
};
//S盒
int S_box[8][4][16] = {
    //S1
    {   {14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7},
		{0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8},
		{4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0},
		{15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13}
	},
	//S2
	{   {15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10},
		{3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5},
		{0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15},
		{13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}
	},
	//S3
	{   {10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8},
		{13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1},
		{13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7},
		{1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}
	},
	//S4
	{   {7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15},
		{13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9},
		{10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4},
		{3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}
	},
	//S5
	{   {2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9},
		{14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6},
		{4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14},
		{11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3}
	},
	//S6
	{   {12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11},
		{10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8},
		{9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6},
		{4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13}
	},
	//S7
	{   {4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1},
		{13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6},
		{1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2},
		{6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12}
	},
	//S8
	{   {13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7},
		{1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2},
		{7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8},
		{2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11}
	}
};
//置换选择P
int P[] = {
        16,  7, 20, 21, 29, 12, 28, 17,
         1, 15, 23, 26,  5, 18, 31, 10,
         2,  8, 24, 14, 32, 27,  3,  9,
        19, 13, 30,  6, 22, 11,  4, 25
};
//子密钥存储空间
char k_children[16][49];
//打印函数
void display(char* str) {
    int i;
    for(i=0; i<strlen(str); ++i) {
        printf("%c", str[i]);
        if((i+1)%8 == 0)    printf(" ");
    }
    printf("\n");
}
//子密钥生成函数
void generate_k_children(char *k) {
    char k_left[33], k_right[33];
    char k_displace[57];
    int i, j;
    for(i=0; i<56; ++i) {
        k_displace[i] = k[IP_1[i]-1];
    }
    k_displace[56] = '\0';
    for(i=0; i<28; ++i) {
        k_left[i] = k_displace[i];
        k_right[i] = k_displace[i+28];
    }
    k_left[28] = '\0';
    k_right[28] = '\0';
    for(i=0; i<16; ++i) {
        for(j=0; j<left_16[i]; ++j) {
            k_left[28+j] = k_left[j];
            k_right[28+j] = k_right[j];
        }
        k_left[28+left_16[i]] = '\0';
        k_right[28+left_16[i]] = '\0';
        strcpy(k_left, k_left+left_16[i]);
        strcpy(k_right, k_right+left_16[i]);
        for(j=0; j<48; ++j) {
            k_children[i][j] = IP_2[j]>28? k_right[IP_2[j]-29] : k_left[IP_2[j]-1];
        }
        k_children[i][48] = '\0';
    }
}
//确定S盒的位置
int locate_x(char b1, char b6) {
    int x = 0;
    if(b1 == '1')   x += 2;
    if(b6 == '1')   x += 1;
    return x;
}
int locate_y(char b2, char b3, char b4, char b5) {
    int y = 0;
    if(b2 == '1')   y += 8;
    if(b3 == '1')   y += 4;
    if(b4 == '1')   y += 2;
    if(b5 == '1')   y += 1;
    return y;
}
//加密函数
void encrypt(char *m, char *c) {
    char m_displace[65];                    //初始置换结果
    char m_left[33];                        //L0-L16
    char m_right[33];                       //R0-R16
    char m_tmp[33];                         //暂存L0-L16
    char e_tmp[49];                         //选择运算结果
    char m_right_tmp[33];                   //R1-R16暂存
    int i, j;                               //i,j临时变量
    int x, y;                               //S盒的坐标
    int res;                                //查询S盒的结果

    //初始置换
    for(i=0; i<64; ++i) {
        m_displace[i] = m[IP[i]-1];
    }
    m_displace[64] = '\0';
    printf("明文置换：   ");
    display(m_displace);

    //分成左右两部分
    for(i=0; i<32; ++i) {
        m_left[i] = m_displace[i];
        m_right[i] = m_displace[32+i];
    }
    m_left[32] = '\0';
    m_right[32] = '\0';
    printf("L0:          ");
    display(m_left);
    printf("R0:          ");
    display(m_right);
    printf("\n");

    //16轮次迭代
    for(i=0; i<16; ++i) {
        printf("N = %d\n", i+1);

        //Li = Ri -1 (i=1, 2, 3 ... , 16)
        strcpy(m_tmp, m_left);
        strcpy(m_left, m_right);

        //选择运算E
        for(j=0; j<48; ++j) {
            e_tmp[j] = m_right[expand_48[j]-1];
        }
        e_tmp[48] = '\0';
        printf("32位输入:    ");
        display(m_right);
        printf("选择运算:    ");
        display(e_tmp);
        printf("子密钥:      ");
        display(k_children[i]);

        //和密钥做模2加法
        for(j=0; j<48; ++j) {
            if(e_tmp[j] == '0' && k_children[i][j] == '0' || e_tmp[j] == '1' && k_children[i][j] == '1') {
                e_tmp[j] = '0';
            } else {
                e_tmp[j] = '1';
            }
        }
        printf("子密钥加:    ");
        display(e_tmp);

        //S盒变换
        for(j=0; j<8; ++j) {
            x = locate_x(e_tmp[j*6], e_tmp[j*6+5]);
            y = locate_y(e_tmp[j*6+1], e_tmp[j*6+2], e_tmp[j*6+3], e_tmp[j*6+4]);
            //printf("x = %2d    y = %2d\n", x, y);
            res = S_box[j][x][y];
            switch(res) {
                case 0:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 1:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 2:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 3:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                case 4:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 5:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 6:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 7:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                case 8:  m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 9:  m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 10: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 11: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                case 12: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 13: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 14: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 15: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                default: m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
            }
        }
        m_right_tmp[32] = '\0';
        printf("S盒:         ");
        display(m_right_tmp);

        //置换运算P
        for(j=0; j<32; ++j) {
            m_right[j] = m_right_tmp[P[j]-1];
        } 
        printf("P置换:       ");
        display(m_right); 

        //和L做模2加法
        for(j=0; j<32; ++j) {
            if(m_right[j] == '0' && m_tmp[j] == '0' || m_right[j] == '1' && m_tmp[j] == '1') {
                m_right[j] = '0';
            } else {
                m_right[j] = '1';
            }
        }

        //第16轮次不交换L和R
        printf("L%-2d:         ", i+1);
        if(i==15)   display(m_right);
        else        display(m_left);
        printf("R%-2d:         ", i+1);
        if(i==15)   display(m_left);
        else        display(m_right);
        printf("\n");
    }

    //逆初始置换
    for(i=0; i<64; ++i) {
        c[i] = _IP[i]>32? m_left[_IP[i]-33] : m_right[_IP[i]-1];
    }
    c[64] = '\0';
}
//解密函数
void decrypt(char *m, char *c) {
    char m_displace[65];                    //初始置换结果
    char m_left[33];                        //L0-L16
    char m_right[33];                       //R0-R16
    char m_tmp[33];                         //暂存L0-L16
    char e_tmp[49];                         //选择运算结果
    char m_right_tmp[33];                   //R1-R16暂存
    int i, j;                               //i,j临时变量
    int x, y;                               //S盒的坐标
    int res;                                //查询S盒的结果

    //初始置换
    for(i=0; i<64; ++i) {
        m_displace[i] = m[IP[i]-1];
    }
    m_displace[64] = '\0';
    printf("密文置换：   ");
    display(m_displace);

    //分成左右两部分
    for(i=0; i<32; ++i) {
        m_left[i] = m_displace[i];
        m_right[i] = m_displace[32+i];
    }
    m_left[32] = '\0';
    m_right[32] = '\0';
    printf("L0:          ");
    display(m_left);
    printf("R0:          ");
    display(m_right);
    printf("\n");

    //16轮次迭代
    for(i=0; i<16; ++i) {
        printf("N = %d\n", i+1);

        //Li = Ri -1 (i=1, 2, 3 ... , 16)
        strcpy(m_tmp, m_left);
        strcpy(m_left, m_right);

        //选择运算E
        for(j=0; j<48; ++j) {
            e_tmp[j] = m_right[expand_48[j]-1];
        }
        e_tmp[48] = '\0';
        printf("32位输入:    ");
        display(m_right);
        printf("选择运算:    ");
        display(e_tmp);
        printf("子密钥:      ");
        display(k_children[16-i-1]);

        //和密钥做模2加法
        for(j=0; j<48; ++j) {
            if(e_tmp[j] == '0' && k_children[16-1-i][j] == '0' || e_tmp[j] == '1' && k_children[16-1-i][j] == '1') {
                e_tmp[j] = '0';
            } else {
                e_tmp[j] = '1';
            }
        }
        printf("子密钥加:    ");
        display(e_tmp);

        //S盒变换
        for(j=0; j<8; ++j) {
            x = locate_x(e_tmp[j*6], e_tmp[j*6+5]);
            y = locate_y(e_tmp[j*6+1], e_tmp[j*6+2], e_tmp[j*6+3], e_tmp[j*6+4]);
            //printf("x = %2d    y = %2d\n", x, y);
            res = S_box[j][x][y];
            switch(res) {
                case 0:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 1:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 2:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 3:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                case 4:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 5:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 6:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 7:  m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                case 8:  m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 9:  m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 10: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 11: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                case 12: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
                case 13: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='1';break;
                case 14: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='0';break;
                case 15: m_right_tmp[j*4]='1';m_right_tmp[j*4+1]='1';m_right_tmp[j*4+2]='1';m_right_tmp[j*4+3]='1';break;
                default: m_right_tmp[j*4]='0';m_right_tmp[j*4+1]='0';m_right_tmp[j*4+2]='0';m_right_tmp[j*4+3]='0';break;
            }
        }
        m_right_tmp[32] = '\0';
        printf("S盒:         ");
        display(m_right_tmp);

        //置换运算P
        for(j=0; j<32; ++j) {
            m_right[j] = m_right_tmp[P[j]-1];
        } 
        printf("P置换:       ");
        display(m_right); 

        //和L做模2加法
        for(j=0; j<32; ++j) {
            if(m_right[j] == '0' && m_tmp[j] == '0' || m_right[j] == '1' && m_tmp[j] == '1') {
                m_right[j] = '0';
            } else {
                m_right[j] = '1';
            }
        }

        //第16轮次不交换L和R
        printf("L%-2d:         ", i+1);
        if(i==15)   display(m_right);
        else        display(m_left);
        printf("R%-2d:         ", i+1);
        if(i==15)   display(m_left);
        else        display(m_right);
        printf("\n");
    }
    //逆初始置换
    for(i=0; i<64; ++i) {
        c[i] = _IP[i]>32? m_left[_IP[i]-33] : m_right[_IP[i]-1];
    }
    c[64] = '\0';
}
int main(void) {
    char m[65];     //明文
    char k[65];     //密钥
    char c[65];     //密文
    printf("\n\n......加密过程......\n\n");
    printf("明文:        ");
    scanf("%s", m);
    printf("密钥:        ");
    scanf("%s", k);
    printf("\n");
    printf("明文:        ");
    display(m);
    printf("密钥:        ");
    display(k);
    generate_k_children(k);
    encrypt(m, c);
    printf("密文:        ");
    display(c);

    char _m[65];     //明文
    char _k[65];     //密钥
    char _c[65];     //密文
    printf("\n\n......解密过程......\n\n");
    printf("密文:        ");
    scanf("%s", _m);
    printf("密钥:        ");
    scanf("%s", _k);
    printf("\n");
    printf("密文:        ");
    display(_m);
    printf("密钥:        ");
    display(_k);
    decrypt(_c, _m);
    printf("明文:        ");
    display(m);

    return 0;
    
}